LEFT JOIN FETCH queries with fresh fetches from the db do not follow JPA Spec
4.4.5.3
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Key: OPENJPA-894
URL: https://issues.apache.org/jira/browse/OPENJPA-894
Project: OpenJPA
Issue Type: Bug
Components: query
Affects Versions: 1.2.0
Environment: Any, tested with Windows
Reporter: Jody Grassel
Discovered what seems to be a break with JPA Specification 1.0, section 4.4.5.3
(Fetch Joins). The query in question uses the LEFT JOIN FETCH sematic, so
there is the expectation that the result list will contain a copy of the entity
reference for every match on the right side of the join (the spec uses the
example with the query "SELECT d FROM department d LEFT JOIN FETCH d.employees
WHERE d.deptno = 1" where 5 employees are members of department(pk=1) the
resultlist should have 5 copies of Department(pk=1). )
Now, if I create all of the entities, persist them to the database, but do not
clear the persistence context (leaving all the new entities managed by the
persistence context still), the query performs as expected. I get multiple
copies of the entity I issued the query for, one for each item successfully
matching the LEFT JOIN FETCH. In the example I will update shortly, I get:
[junit] --------------------------------------------------
[junit] Executing testQuery001
[junit] Executing named query getAGroup with intData=42 ...
[junit] ResultList size: 8
[junit] 1 EntityA(id=1): 42, Entity A - PK 1
[junit] 1 EntityA(id=1): 42, Entity A - PK 1
[junit] 1 EntityA(id=1): 42, Entity A - PK 1
[junit] 1 EntityA(id=1): 42, Entity A - PK 1
[junit] 1 EntityA(id=2): 42, Entity A - PK 2
[junit] 1 EntityA(id=2): 42, Entity A - PK 2
[junit] 1 EntityA(id=2): 42, Entity A - PK 2
[junit] 1 EntityA(id=2): 42, Entity A - PK 2
However, if I clear the persistence context, forcing OpenJPA to make a fetch
from the database, I only get unique instances of the entity I issued the query
for, not multiple copies for each match on the right side of the join.
[junit] --------------------------------------------------
[junit] Executing testQuery002
[junit] Clearing persistence context...
[junit] Executing named query getAGroup with intData=42 ...
[junit] ResultList size: 2
[junit] 1 EntityA(id=1): 42, Entity A - PK 1
[junit] 1 EntityA(id=2): 42, Entity A - PK 2
Both tests use the exact same code for everything, except testQuery002 does a
em.clear() before running the query.
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